Modeling organic thin-film transistors based on the virtual source concept: A case study
•A novel compact DC model of organic thin-film transistors is suggested.•Diffusive charge emission from a virtual source is a suitable concept for TFT modeling.•Charge trapping has a similar effect as a gate bias dependent mobility.•A pronounced linear output curve at low drain bias points to a larg...
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Published in | Solid-state electronics Vol. 161; p. 107639 |
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Main Authors | , |
Format | Journal Article |
Language | English |
Published |
Elsevier Ltd
01.11.2019
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Subjects | |
Online Access | Get full text |
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Summary: | •A novel compact DC model of organic thin-film transistors is suggested.•Diffusive charge emission from a virtual source is a suitable concept for TFT modeling.•Charge trapping has a similar effect as a gate bias dependent mobility.•A pronounced linear output curve at low drain bias points to a large serial resistance.•DC characteristics of OTFTs yield informations about the carrier mean free path.
We apply the virtual source concept to describe the DC current-voltage characteristics of organic thin-film transistors. The draining of charge carriers from the virtual source is calculated using emission-diffusion theory. The electrical characteristics of organic thin-film transistors are commonly analyzed employing a drift mobility that is enhanced by the transistor overdrive. One possible origin of such a mobility model is charge trapping. We show that the direct parametrization of the fraction of mobile to total charges including trapped ones allows for a straight forward adaptation of the virtual-source emission-diffusion theory to organic electronics capable of describing measured transfer and output curves with a small number of parameters. The resulting model offers an alternative parametrization of well-known bias and temperature dependences. Beyond others, a limited charge injection does not arise from the high-field bulk saturation velocity but from the unidirectional thermal velocity and the charge carrier mean free path is a critical model parameter. Moreover, diffusivity replaces the drift mobility as the current scaling factor, which would lead to slightly different predictions for the current-voltage curves in the case that the Einstein relation is not valid. |
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ISSN: | 0038-1101 1879-2405 |
DOI: | 10.1016/j.sse.2019.107639 |